The Calaveras County Sheriff's office said Saturday that the man was considered armed and dangerous, and authorities are warning residents in the country town to lock their doors.

The office declined to release details on the slaying.

NBC's Sacramento affiliate KCRA reported the victim's 12-year-old brother encountered an intruder in his home and saw the man run away. The boy went to check on his sister and found she had been stabbed.

The girl was later pronounced dead at a hospital.

Valley Springs is a town of about 3,500 some 60 miles southeast of Sacramento.